American highway standards are set by the American Association of State Highway Transportation Officials (AAHSTO) and then adopted by the FHWA. These standards are published in a book called the AASHTO Green Book "A Policy on Geometric Design of Highways & Streets", (note the base word in Geometric) which has a 1994 date and is 100% metric. I think English States are still using the 1990 English version which is slightly different than the 1994 version. My guess is the next version will be dual units to accommodate those States that still use English. This means thought there will be two sets of similar although different Highway Geometric Standards. There is no reason, and I doubt any State DOT has, to use a soft conversion of the English Standards (ie. 1"=25.4 m) when AASHTO is available. Also, the US chose what I think is a more rational approach to lane width. We use 3.0 m, 3.3 m and 3.6 m wide lanes which corresponds nicely to 10, 11 & 12 feet. I can not see building road widths to the nearest 100th of a meter. Shoulder widths are in similar .3 m increments Howard Ressel, Metric Manager New York State Department of Transportation, Region 4 >>> "Gregory Peterson" <[EMAIL PROTECTED]> 11/20/00 11:44am >>> <snip> The following is a basic summary of a 1 hour (36 hs) discussion with Mr. Peter Brier of the Ministry of Transportation, Ontario (MTO) regarding Ontario's conversion in the 1970s.
